CD4 response of QuantiFERON-TB Gold Plus for positive consistency of latent tuberculosis infection in patients on dialysis

A significantly negative reversion in the QuantiFERON-TB Gold In-tube (QFT-GIT) test is reported in patients on dialysis, which makes the results unreliable. The CD4 and CD8 responses of the QFT-Gold plus (QFT-Plus) may have better positive consistency, but this needs to be investigated. We enrolled dialysis patients with baseline positive QFT-GIT(0) results and conducted two rounds of follow-up paired QFT-GIT(1&2) and QFT-Plus(1&2) tests at an interval of 6 months. The positive consistency, concordance, and discordance of the QFT results were analyzed. A total of 236 patients on dialysis were screened, and 73 participants with positive QFT-GIT(0) results were enrolled. The baseline QFT-GIT(0) response was higher in the 1st QFT-Plus(1)(+) group than in the QFT-Plus(1)(−) group, but insignificantly different between the 1st QFT-GIT(1)(+) and QFT-GIT(1)(−) groups. The two assays had good correlation when concurrently tested. Fifty-three subjects completed a second round of the QFT-GIT(2) and QFT-Plus(2). Persistent positivity was higher with the QFT-Plus(2) (81.8%) than with the QFT-GIT(2) (58.8%, p = 0.040). The QFT-GIT(1) and QFT-Plus(1) CD4 responses were higher in patients with persistent positivity than in those with negative reversion, whereas the difference of the QFT-Plus TB1 and TB2 data, representative of the CD8 response, were similar between positive persistence and negative reversion. In conclusion, the QFT-Plus provides more reliable positive consistency than does the QFT-GIT. The CD4 interferon-γ response might play a role in maintaining positivity of LTBI.